Question
What is the major function of an antenna tuner (antenna coupler)?
Answer Options
- A) It matches the antenna system impedance to the transceiver’s output impedance
- B) It helps a receiver automatically tune in weak stations
- C) It allows an antenna to be used on both transmit and receive
- D) It automatically selects the proper antenna for the frequency band being used
Correct Answer: A
Explanation
An antenna tuner (or Transmatch) is a device that uses internal adjustable components (inductors and capacitors) to transform the complex impedance presented by the antenna system (T5C05). Its major function is to match the antenna system impedance to the transceiver’s output impedance (which is always 50\text{ Ohms} - T9B02).
By matching the impedances, the tuner forces the SWR seen by the transceiver down to 1:1 (T7C04). This tricks the transmitter into thinking it is feeding a perfect load, which allows the transmitter to safely deliver full power without engaging its protective circuits (T7C05).
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